The shared interest groups most people are involved in in their regular lives are far too small to make any extrapolation to the larger population.

Also, for many human traits (i.e height), the intra-population variation is much greater than the inter-population variance, especially when controlling for the effect of environment.

We have a tendency to anchor our biases on the extreme examples of any population when we form our biases, often through mediums like elite/pro sports which select those at the extremes.